Louassaa Khalil, Guerrero Josep M, Boukerdja Mahdi, Chouder Aissa, Khan Baseem, Cherifi Abdelhafid, Yousaf Muhammad Zain
Center for Renewable Energy and Microgrids, Huanjiang Laboratory, Zhejiang University, Zhuji, 311816, Zhejiang, China.
Center for Research on Microgrids (AAU CROM), AAU Energy, Aalborg University, 9220, Aalborg, Denmark.
Sci Rep. 2025 Feb 27;15(1):7061. doi: 10.1038/s41598-025-89318-0.
In recent years, DC microgrids supplying constant power loads (CPLs) have attracted significant attention due to their impact on overall system stability, which is attributed to their electrical characteristics that exhibit negative incremental impedance. This paper examines a secondary control strategy aimed at ensuring accurate power sharing and voltage restoration within an islanded DC microgrid supplying a constant power load. The droop control function is typically used in the primary control layer to facilitate power sharing among distributed generators (DGs). However, differing load profiles may cause the DC bus voltage to deviate from its nominal value. To restore the DC bus voltage to its nominal value while maintaining accurate power sharing, a primary and secondary control scheme is proposed. This scheme employs an integrated control strategy combining sliding mode control for the primary control level and H-infinity control for secondary control. The approach is based on a two-time-scale stability analysis, i.e., the settling time of the primary control must be faster than that of the secondary control. Additionally, compared to most existing methods, the proposed approach requires no global information and depends exclusively on DC bus voltage feedback, eliminating the need for passive loads in parallel with the CPL. A test system of an islanded DC microgrid feeding a CPL is created using Matlab and PSIM software to assess the proposed method. An experimental prototype comprising two DGs and a tightly voltage-controlled boost converter emulating a CPL is developed to demonstrate the proposed approach and confirm the theoretical results.
近年来，由于对整个系统稳定性的影响，为恒功率负载（CPL）供电的直流微电网引起了广泛关注，这归因于其呈现负增量阻抗的电气特性。本文研究了一种二次控制策略，旨在确保在为恒功率负载供电的孤岛直流微电网内实现精确的功率分配和电压恢复。下垂控制功能通常用于一次控制层，以促进分布式发电机（DG）之间的功率分配。然而，不同的负载曲线可能会导致直流母线电压偏离其标称值。为了在保持精确功率分配的同时将直流母线电压恢复到其标称值，提出了一种一次和二次控制方案。该方案采用了一种集成控制策略，将一次控制级的滑模控制和二次控制的H无穷控制相结合。该方法基于双时间尺度稳定性分析，即一次控制的调节时间必须比二次控制的调节时间快。此外，与大多数现有方法相比，该方法不需要全局信息，仅依赖于直流母线电压反馈，无需在恒功率负载上并联无源负载。使用Matlab和PSIM软件创建了一个为恒功率负载供电的孤岛直流微电网测试系统，以评估所提出的方法。开发了一个由两个分布式发电机和一个模拟恒功率负载的严格电压控制升压转换器组成的实验原型，以演示所提出的方法并验证理论结果。
